Mounting for stencil screens



Oct. 9, 1951 c. F. scHAi-:FER

MOUNTING FON STENCIL SCREENS Filed Nov. l, 1945 f gether.

Patented Oct. 9, 1951 UNITED STATES- PATENT OFFICE 2,571,064 Y MOUNTINGFOR STENCIL SCREENS Charles F. Schaefer, Westport, Conn.

Application November 1, 1945, Serial No. 626,051

This invention relates to a coating and printving machine of the type inwhich there is a rotatinghollow drum carrying a stencil screen throughwh1ch the coating material, such, for example, as an adhesive or ink, isforced from the inte- 'rior of the drumA to the paper, cardboard, or

other article, to which the coating material is to be applied, and hasfor an object to provide an improved type of mounting for the coatingscreen and one in which the stencil member is held in the properposition, but which, both before and after use, can be laid out flat sothat it may be economically stored or transported, as in this conditionit requires a minimum of space.

With the foregoing and other objects in view, I have devised theconstruction illustrated in the accompanying drawing forming a part ofthis specification. It is, however, to be understood the device is notlimited to the specic details of construction and arrangement shown, butmay emand the stencil sheet and mounting therefor are A greatlyexaggerated. The device comprises a hollow rotary cylindrical drum 5,which may be of sheet metal closed at its opposite ends so as to providea container for coating material, mounted at its opposite ends onsuitable supporting rollers 6 which may be driven by any suitable means(not shown) to rotate the drum 5. Such means may, for example, be suchas that shown in my prior patent for Stencil Coating Machine,

No. 2,382,920, issued August 14, 1945, and there lmay be a lowerpressure rollerY 'I to support the work and hold it against the surfaceof the stencil during the coating operation and insure that kthe articlebeing coated and the stencil move to- This may be mounted on yieldable.the roller against the drum. Supports or tables I and II may also beprovided for the work .-12 at. vthe forward and rear sides ofthe drum 6Claims. (Cl. 101-120) to guide the work into the coating position andreceive it after it leaves this position, and the tables are mounted onmeans whereby they may be adjusted up and down or toward and from thedrum to properly locate them for work of different thicknesses. Anysuitable adjusting means may be employed, that shown being a hand nut I3on a screw I4 and supported on any suitable support I5. Spring means mayalso be provided to yieldingly press the drum against the supportingrollers 6 to secure the proper traction and also prevent the drum beinglifted from the rollers during the coating operation. In the drawingthis is shown as a pair of rollers I6 engaging the top of the drum atthe opposite ends thereof and mounted on a connecting support I1 pivotedat IB on a supporting arm I9 which is in turn pivoted at 2'0 on theframe 2| of the machine with a spring 22 pulling this lever downwardlyto press the roller I6 against the drum. A set of these pressure rollersmay be provided at each end of the drum beyond the stencil so as not tointerfere with it. The springs 22 should be heavier than the springs 9for the pressure roller so that these latter springs will not lift thedrum from the driver rollers 6.

In one side of the drum is a large opening or window '23 over which islocated the stencil 24 for applying the coating to the Work. Thisstenci] is mounted on a large flexible sheet 25 and cemented theretoover a large opening or window 26 in this sheet. The stencil is largeenough to overlap the edges of the opening 26 in the exible sheet 25 onall sides, and the ilexible sheet 25 is of a width to overlap the windowor opening 23 in the drum 5 on all sides. This flexible sheet, however,is preferably of a length to extend throughout the entire circumferenceof the interior of the drum, and may be`overlapped at its ends asindicated at 21 and these ends cemented together, or these ends may beabutting or even spaced from each other and cemented to the interior ofthe drum. In either case, the exible sheet 25 carrying the stencil 24 issecurely mounted and held in the drum against movement or creepingduring the coating ope'ration.

The stencil 24 could be mounted on the inner side of the exible sheet25, but it is preferably mounted on the outside, as shown in Fig. 1,because this secures several material advantages. The stencil ispreferably larger than the opening or window 23 in the drum so that itoverlaps the edges of this opening, as shown at 28, and .also theopposite endsof the opening, because when it does this, pressure fromthe inside of the drum forcing the coating material through the stencil,does not then tend to separate the stencil from the supporting sheet orthe drum, because 4the pressure holds it between the sheet and the drum.A very material advantage of having the flexible stencil mounted on theoutside of the .flexible sheet 25 is that when the sheet is applied tothe interior of the drum 5 and rolled up into the cylindrical shape, itautomatically stretches -or forms the stencil into a true arc of acircle, Vso that there are no wrinkles or other parts out of position,and it definitely retains this shape.

The stencil element 24 may be of plain flexible porous material topermit passage of the coating material and form a uniform coating una`work of the size and shape of the window or. opening 26 in the flexiblesheet 25, or a mask 29 could be applied to the stencil to block outcertain portions of it so that the coating material would be .applied.ina desired design, or portionsofthe stencil itself couldbe blocked outby any suitable material, such, for example, as lacquer, to pre- .ventpassage of .the coating materialat. certain portions of its surface tothusapplythe .coating in various designs.

The interior chamber of the drum 5. preferably forms a reservoir orcontainer for a considerable .amount of the coating material indicatedat3D,

.andas described in my prior patent abovenoted, .and located within thischamber and extending `longitudinallyof the drum and immersed inV thismaterial is .a'suitable pressure device, such asa roller or other typeof squeegee 3|, pressing .against the inner surface of the .flexiblemounting sheet 25 and the stencil to force the coating .material throughthe stencil as it passes under .this pressure device, and thus apply thecoating material to the Work l2 as it passes between the .drum and thepressure roller 1. The pressure Vdevice 3|.is yieldably vmounted inanysuitable manner, such, for. example, as by yieldable bear- .ings 32for the supporting shaft or trunnions 33,

.and pressed against the drum by suitable ysprings 34,. Temperaturecontrol means for the coating material may be provided, as described inmy prior patent above noted.

This construction and arrangement ,comprising the combination of. aflexible sheet 25 with the .window or opening vin it to be located overthe window or opening in the drum 5, to which flexible sheet can beadhered a screen or other suitable stencil element, this combination offlexible screen or stencil to be inserted or` mounted in the hollowrotatable drum, as described, is of material advantage over the oldstructures. It may be used with any hollow type of drum used forprinting and coating purposes, and in the present case the term coatingis used inthe broad sense of either applying a coating toan extensivesurface, either to merely cover the surface or provide an adhesive to-which otherarti- Vclesmay be applied, or to apply a coating such asadhesive in a given design, or as printing with ink or other materialsof various colors, printing being in reality the application of certaincoating material in given designs. It is preferred to use it asillustrated, with an amount of the coating material in the drum whichforms a container for it, but other suitable feeding devices forsupplying the material to the stencil and forcing it therethrough may beused, the principal im- -provement being the mounting of the flexibleVVVscreen or stencil on the flexible supporting sheet, und then mountingthiscombination on the in-v fside of the rotatable'drum. There arenumerous 4 advantages secured by this. It permits the ready insertion,removal and storage and re-use of this screen or stencil, and by placingit on the inside of the drum the difliculty of confining the solution inthe drum when the screen is mounted or wrapped on the outside of thedrum is overcome because with this arrangement the pressure from theinside of the drum merely presses the screen against the walls of thedrum, while if the screen were wrapped on the outside of the drum, as is.the old and common method of mounting it, the pressure tends to forcethe screen away from the drum, permitting the coating material to flow.out around the edges between the drurri and the screen. After thecoating operation the flexible mounting .Sheet 25 with the stencilscreen can be removed from the drum and laid flat, for conlvenient,economical and safe storage, in condition to be readily used again whendesired. In this condition it requires a minimum of space in storage....'I.he. stencil screen can be of flexible cloth. or.v metal or. other;suitable. porous ,material `through which .the liquid orsemi-liquidcoating material may pass to the surface to Vbe coated. Theflexible mounting or supporting .sheet 25 can be ofv any suitableflexible sheet material, such, for example, as metal, rubber, plastic,.wire screen, fabric, cardboard, paper, fiber, or anything strong enoughto hold together and support the stencil. In mounting it in the drumitcaribe either cemented to the drum or heldby Suitable .clamping meanswithin the drum, as desired. As suggested, for different designs a maskcan be placed over the stencil screen, as indicated at129, to block offparts of the screen for various `designs, or a design could be cut inthe mask,..or parts of the screen itself could be blockedV off toprevent passage of the material. and make 'the design. .If thesupporting flexible sheet`25 were made of metal screen or some porousmaterial, the part thereof within the window or opening`23 of the drumcould itself form the stencil screen, and parts could be blocked out b y`some'thlck solution or` cement, so the coating solution will be forcedonly through openings of the design or the stencil sheet.

-Having thus set forth the nature of my invention, what I claim is:

1, In a machine of the character described, a hollow rotatable drumprovided with a relatively large opening in its side wall, a flexiblesheet supportlarger than saidiirst opening and itself provided with arelatively large opening in alignment with the opening in the drum,ailexible porous material adapted for lpassage of a coatingmaterialsecured to said flexible sheet over theopen- Aing therein, said flexiblesheet being mounted at the inner side of the side wall of the drum andlocated with the porous'material over the opening in the drum, theporous material being larger than the opening in the flexible sheet soas to overlap opposite edges of said opening, and pressure means withinthe drum for forcing a coating material `through the'porous material toan article outside the drum.

2. A stencil coating machine of the character described comprising ahollow rotatable drum provided with a window in its side wall,theinterior chamber of said drum forming a container for a quantity ofsemiliquid coating solutlon,ra flexible supporting sheet mountedv on theinside of the drum over said window. and extending on .the inner surfaceof the closed side wall of the drum beyond the sides/of the window, saidsheet being provided .with a relatively largeopeningjn 'valignment :with.the -windows'. :a .flexible percus` e stencil mounted on and secured tothe flexible sheet over said opening, said stencil being larger than theopening in the supporting sheet so as to overlap opposite edges thereof,p-ressure means within the chamber in the drum extending longitudinallythereof and immersed in the solution in the lower part of the drum toforce the solution through the stencil as the drum rotates, means forrotating the drum, and means for retaining the article to be coatedagainst the outer surface of the drum.

3. In a stencil coating machine of the character described, a hollowrotatable drum provided with a window in its side wall, a exiblesupporting sheet provided with a relatively large opening thereinmounted on the inner side of the closed side wall of the drum so as toconform to the curvature thereof and arranged with its opening inalignment with the window in the drum, a exible stencil mounted on theouter curved surface of said flexible support over the opening thereinand overlapping the edges of the window in the drum between the saidsupport and the inner surface of the drum, pressure means within thedrum extending longitudinally thereof and engaging the inner surface ofsaid sheet and stencil to force coating solution through the stencil asthe drum is rotated, means for rotating the drum, and means forretaining the article to be coated against the outer surface of thedrum.

4. In a stencil coating machine of the character described, a hollowrotatable drum provided with a window in its side wall, a flexiblesupporting sheet mounted on the inside of the side wall of the drum oversaid window so as to conform to the curvature of the drum, said sheetbeing provided with a relatively large opening in alignment with thewindow, a exible stencil mounted on the outer curved surface of saidsupporting sheet over the opening therein and larger than said window soas to overlap opposite side edges of the window between the supportingsheet and the inner surface of the drum, the interior chamber of saiddrum forming a container for a quantity of semiliquid coating solution,pressure means within the chamber in the drum extending 1ongitudinallythereof and immersed in the solution in the lower part of the drum toforce the solution through the stencil as the drum rotates, means forrotating the drum, and means for retaining the article to be coatedagainst the outer surface of the drum.

5. A stencil coating machine of the character described comprising ahollow rotatable drum provided with a window opening in its side Wall, aexible supporting sheet provided with a relatively large opening thereinmounted on the inner side of the curved side wall of the drum so as toconform to the curvature thereof and extend beyond the edges of thewindow opening, said sheet being arranged with its opening in alignmentwtih the window opening in the drum, a flexible stencil mounted on thesupporting sheet over the opening therein and larger than this openingso as to overlap the supporting sheet around this opening and secured tothis sheet, pressure means within the drum extending longitudinallythereof at the inner surface of said sheet and stencil to force coatingsolution through the stencil as the drum is rotated, means for rotatingthe drum, and means for retaining the article to be coated against theouter surface of the drum.

6. A stencil coating machine of the character described comprising ahollow rotatable drum provided with a window opening in its side wall, aflexible supporting sheet provided with a relatively large openingtherein mounted on the inner side of the curved side wall of the drum soas to conform to the curvature thereof and extend beyond the edges ofthe window opening, said sheet being arranged with its opening inalignment with the Window opening in the drum, said flexible sheetextending throughout the entire circumference of the interior of thedrum, a exible stencil mounted on the supporting sheet over the openingtherein, said stencil being larger than this opening so as to overlapthe sheet about the opening and secured thereto, means within the drumat the inner surface of the exible sheet and stencil to force coatingsolution through the stencil as the drum is rotated, means for rotatingthe drum, and means for retaining the article to be coated against theouter surface of the drum.

CHARLES F. SCHAEFER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 513,212 Stackhouse Jan. 23, 1894553,805 Deckert Jan. 28, 1896 2,191,134 Playford Feb. 20, 1940 2,419,695Shuttleworth Apr. 29, 1947

